1. Field of the Invention
The present invention relates to the lightening of the skin, hair, nails and/or lips. The present invention further relates to compositions and methods for lightening the skin, hair, nails and/or lips.
2. Description of the Prior Art
Consumers, particularly those in Asia, have sought to lighten and reduce uneven pigmentation in the skin. Common skin conditions treated include freckles, age spots, dark spots, hyperpigmentation, discoloration, melasma, yellowing, and dark circles under the eyes.
Numerous substances have been applied to the skin to lighten the skin. Such substances include hydroquinone, kojic acid, licorice and/or its derivatives, ascorbic acid/ascorbic acid derivatives, arbutin, bearberry, Glycyrrhiza glabra and its derivatives, Chlorella vulgaris extract, perilla extract, and coconut fruit extract. Perilla extract is disclosed as a whitening agent in U.S. Pat. No. 5,980,904 and Japanese Publications 07025742, 07187989, 10265322, 2001163759, and 2001181173. Coconut fruit extract is disclosed as a whitening agent in Japanese Patent No. 2896815 B2. An extract of spongy mass of coconut tissue is employed in a tanning sunscreen composition in U.S. Pat. No. 5,756,099.
Skin and hair pigmentation is determined by the level of melanin present in the epidermis and hair fiber, respectively. Three different types of melanin are present in, for example, the epidermis: DHI-melanin, DHICA-melanin and pheomelanin. The different types of melanin vary in color or shade. DHI-melanin is the darkest and is blackish in color. DHICA-melanin is brownish in color. Pheomelanin is the lightest and is reddish in color.
Melanin is synthesized in specialized organelles called melanosomes within pigment-producing cells (melanocytes). Melanocytes respond to stimuli to regulate melanin synthesis.
Most conventional topical lightening agents act by interfering with the action of tyrosinase, the enzyme that catalyzes the conversion of the amino acid tyrosine to DOPAquinone. Previously, it has not been known that hypopigmenting could be achieved by inhibiting enzymes “downstream” from tyrosinase in the melanin synthesis pathway. It has now been discovered that the use of a melanin synthesis regulating agent that inhibits DOPAchrome tautomerase and/or DHICA-polymerase results in a composition with superior lightening, especially skin lightening.
It would be desirable to have a topical composition that provides enhanced levels of lightening, bleaching, hypopigmenting, whitening and/or depigmenting (hereinafter referred to individually and collectively as “lightening” or “lighten”). It would be further desirable to have a topical composition that contains lightening agents that acted to interfere with the conversion of DOPAchrome to DHI-melanin and DHICA-melanin. It would be yet further desirable to have a topical composition that contains lightening agents that act to inhibit or prevent the transfer (uptake) of melanin from the melanocytes to the keratinocytes. It would still yet be further desirable to have methods for lightening the skin, hair, nails and/or lips employing the compositions of the present invention.